The invention relates to a soot-particle filter for after-treatment of the exhaust gases of diesel engines by oxidation and the supply of thermal energy, having supporting tubes which extend in the filter housing next to one another, which supporting tubes are closed at one end face and are provided at the other end face with a clean-gas outflow opening and on which there is applied at least one catalytic filter winding, via which exhaust gases flow radially from outside to inside into the permeable supporting tubes.
Such a soot-particle filter is known from German Patent Document De 38 28 516 C1 and comprises numerous supporting tubes which extend in the filter housing with parallel axes and which are of a perforated design and on which a ceramic yarn is wound crosswise in a multi-ply manner as a filter layer. The supporting tubes are closed at one end face and are provided at the other end face with a clean-gas outflow opening, as a result of which the exhaust gases flowing into the filter housing pass radially from outside to inside through each filter layer and each perforated supporting tube and emerge as a clean gas from the outflow openings of the supporting tube.
An object of the invention is to further improve a soot-particle filter of the generic type with a view to lowering the emission of pollutants, without at the same time increasing the overall dimensions of the soot-particle filter.
This object is achieved according to preferred embodiments of the invention by providing an arrangement wherein an elongated, exhaust-gas-permeable insert with a catalytically effective surface is provided in each supporting tube.
The pollutant fractions in the exhaust gas can be further reduced by the surface-enlarging measures within the soot-particle filter, namely in the hollow space of the supporting tubes. Consequently, in spite of retaining the overall dimensions of the soot-particle filter, a further reduction in the emission of pollutants can be realized in a simple way.
The inserts with various types of support geometries are also suitable as a retrofitting kit for fitting at a later date into the supporting tubes of the soot-particle filters described at the beginning.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.